Upgrade to Neo4j 2.0 - new module blueprints-neo4j2-graph

* adapted API and SPI changes
* added label support for Neo4jVertex
* added minimal Cypher support to Neo4jGraph (mostly for schema index operations)
* fixed blueprints-tests by adding an constantly open outer transaction which is also restarted after commit or rollback in Neo4jTestGraph
Issue https://github.com/orientechnologies/orientdb/issues/1604 ridset global lock was removed.
added Neo4j2 graph support via Michael Hunger pull request.
renamed to Neo4j2Graph -- and all other respective classes.
no longer is Java6 supported as Neo4j2 requires Java7+.
added autoStartTransaction to all read-based methods.
Merge branch 'master' of https://github.com/tinkerpop/blueprints
fixed all NotInTransaction issues in Neo4j2 and removed the need for the wrapper graph provided by Hunger.
CompareRelation was renamed to Predicate the next day.
Add a forWrite flag to Neo4j2's autoStartTransaction method.